1. Technical Field
Exemplary embodiments relate generally to semiconductor memory devices, and more particularly to nonvolatile memory devices and memory systems including the nonvolatile memory devices.
2. Description of the Related Art
Semiconductor memory devices may be respectively categorized as nonvolatile or volatile in nature according to their ability or inability to retain stored data in the absence of applied power. A magnetic random access memory (MRAM), which is a kind of the nonvolatile memory device, has characteristics such as the high integration equal to that of a dynamic random access memory (DRAM), the speed faster than that of a static random access memory (SRAM), and the power consumption lower than that of the DRAM or the SRAM.
However, since the MRAM employs a current sensing method, column and row addresses must be simultaneously designated upon a read/write operation. Both of n row address terminals and n column address terminals must be simultaneously provided, and thus 2n address terminals are required in the MRAM. As the number of address input terminals is increased, the packaging cost of a memory chip may rise. The increase of the packaging cost of the memory chip becomes one of major problems in lowering the product cost of the MRAM.
In addition, the MRAM may not be compatible with DRAM access environment in which the access to a memory cell is performed by sequentially applying an n-bit row address signal and an n-bit column address signal. To compatibly employ the MRAM under the conventional DRAM access environment, an address bus structure must be established between a memory controller and a DRAM memory, and an address bus structure dedicated for another MRAM must be additionally established, which results in a complex hardware and software system design.